Rainfall likely caused steam at Fukushima reactor

Visitors and workers are required to wear protective suits and masks at Japan's Fukushima nuclear power plant, which was rocked by the March 11, 2011 tsunami and earthquake.

Worrisome steam seen rising from a building that houses a reactor at Japan's Fukushima Daiichi nuclear plant was likely caused by rainfall, said power company representatives on Thursday, but no emergency situation appears to be imminent.

The "steam-like gas found wafting through the air" above the building that houses Reactor No. 3, according to a Tokyo Electric Power Company (TEPCO) press release, was spotted on a live camera feed of the building and immediately aroused international concern.

"We think it's possible that rain made its way through the reactor building and having fallen on the primary containment vessel, which is hot, evaporated and created steam," said Mayumi Yoshida, a TEPCO spokeswoman, according to the Guardian.

Levels of radioactivity around the plant remain the same, and workers are looking to verify the cause of the emission, writes Reuters. Extremely high levels of radiation remain around the roof of Reactor 3, making it too dangerous for workers to approach.

Workers had been on standby to inject boric acid into the reactor to stave off a nuclear chain reaction, reports the New York Times, although it appears these measures will not be needed.

According to the Times, any problems with Reactor 3 are particularly worrying because it contains dangerous mixed uranium-plutonium oxide fuel, as well as a fuel pool filled with 500 radioactive rods.